1. Field of the Invention
The invention relates to waste containers and more particularly to sealable holding tanks for portable toilets, hospital "sharps" containers and operating room "kick buckets."
2. State of the Art
Holding tanks constitute a principal component of portable toilets of the type installed in recreational vehicles or in free-standing shelters. Holding tanks are typically emptied by pumping or gravity induced draining. Tanks which are emptied by pumping are commonly open to the environment having no liquid-proof seal, containment being effected only by the wall of the tank. Such an open tank thus relies on remaining upright to prevent spills. A pumped tank must be emptied by a hose drawing the tank's contents into a tank truck for hauling to a disposal site. Alternatively, the tank may be taken to a disposal site for pumping directly into a receptacle or sewage line.
Drainable tanks are found in recreational vehicles including motor homes and boats. A drain penetrating a wall of the tank is positioned to empty from the lowest point in the tank through an attachable hose into a receptacle at a dumping station. A closure selected from one of several available designs, selectively opens and closes the drain. Closures typically involve gate valves, ball valves, blade valves, flapper valves or the like. These closures must be sealed by `O` rings, face seals or the like. Each seal has a compressible, resilient member (the seal) having a surface contacting a corresponding surface of a harder, structural member (the gate or valve element). Face seals rely on direct pressure of the face seal against a corresponding surface, while `O` rings rely on resilient rings protruding slightly to contact a surface from retaining grooves into which the `O` rings are inserted.
In closures, the resilient seals eventually break, wear, age, cut, rot, deform, relax or otherwise fail to seal. Moreover, the closures tend to be mechanically complex or intricate, subjecting themselves to breakage, warpage, or other mechanical failures of costly parts that are not easily replaced. Also, closures not only trap debris in crevices, grooves, gaps and slots, they tend to prevent access for easy cleaning of a holding tank. Tanks may be substantially emptied but not cleaned.
Portable holding tanks with their large size, connections and fixtures are not, in reality, easily portable, nor are they sealed to tolerate being tipped, or turned upside down (upended). These last considerations are important in back country travel such as river rafting, wilderness hiking and the like where human impact must be minimized. In some areas, virtually all solid waste must be contained and carried out by travelers or maintenance workers.
Another type of holding tank is a hospital "kick bucket" that comes in a variety of configurations for receiving wastes, typically those generated in an operating room. Likewise, a "sharps" container must be puncture proof, sealable, and durable, yet easily accessible for receiving and holding needles, scalpels, glass and other sharp objects for later disposal or recycling.
A sealable containment vessel capable of performing these functions is desirable.